I don't think the cartridge matters as much as the person behind the trigger. If someone knows they can make a clean kill with a certain round, and then does, what else matters? How dead do you want a deer?
I hunted with a 300-221 loaded to around 1900 fps with a 125BT and it did the job on the Texas white tails and axis deer. I have been playing with that same round with a 1/8 barrel for suppressed subsonic, but have not used it in the field yet. In any case I think Martinetta went over that round better than I could.
I then used a 6.8, no problems there either. This pig dropped in its tracks with one shot.
Here is the
link to a video of two pigs with one shot from the 6.8. The back pig dropped, the front one ran about 10 yards and was dead under that bush when I got there.
A couple of years ago some friends and I went hunting in the Texas hill country and besides the 6.8 we were also using the 7.62x40 and a .25x40. Those last two cartridges were developed by Kurt B. right here in SW Louisiana. The 7.62x40 was later renamed Wilson Tactical by the Wilson team, but
this thread will show that Kurt was posting about it back in 2008, and I want to point out that Kurt deserves the credit for the cartridge. On that link, if you go to Kurt's post of 10/13/2010, there are some pictures of the results of shots from those calibers. Both of those wildcats were impressive in their killing ability.
Finally, although I have never hunted with a .223, a friend of mine got a single shot 223 for his daughter, and so far she has killed everything she has drawn a bead on. Here are a couple of videos he took. She was shooting 70 grain bullets. While I personally don't feel comfortable shooting deer with a 223, it is hard to argue with the results.
http://www.youtube.com/watch?v=Skky-pIjYVo&feature=youtu.behttp://www.youtube.com/watch?v=OjgNxb-UuvI&feature=youtu.be